Article 430 of the French Code of civil procedure
The court shall be composed, on pain of nullity, in accordance with the rules relating to judicial organisation. Challenges relating to its regularity must be presented, on pain of inadmissibility, as soon as the debates are opened or as soon as the irregularity is revealed if it occurs subsequently, failing which no subsequent nullity may be pronounced on this count, even of its own motion. The provisions of the preceding…